OK this is CPU bound, much precalculating required

main.c

@@ -30,7 +30,10 @@
 #include "bun.h"
 
 /**
- * This barely gets 50fps on an A1200 but I'm leaving it for now. Potential improvements:
+ * This barely gets 50fps on an 020 but I'm leaving it for now.
+ * The demo is definitely CPU bound.
+ *
+ * Potential improvements:
  *
  * [ ] Precalculate even more of bun.c. This may get 50fps on an A500 if I do this.
  *     It would require more significant caching of as much stuff as possible.
@@ -374,6 +377,7 @@ int main(void) {
     if (i > FRAMES_FOR_SCREEN) i = 0;
   }
 
+  // somthing in here causes an A500 in KS 1.3 to crash
   giveBackSystem();
   teardownKeyboard();